title: The 7-valent pneumococcal conjugate vaccine elicits cross-functional opsonophagocytic killing responses to Streptococcus pneumoniae serotype 6D in children.
abstract: BACKGROUND
  We investigated the immune response to serogroup 6 with the opsonophagocytic killing assay (OPKA) in children aged 12-23 months of age after immunization with the 7-valent pneumococcal conjugate vaccine (PCV7) containing serotype 6B.
  
  
  METHODS
  Blood samples were obtained from 59 children who had blood sampling for medical examination. Immunization status against PCV7 was confirmed by immunization records and samples were categorized according to immunization status into a booster, primary, or control group. The OPKA was performed for serotypes 6A, 6B, 6C, and 6D.
  
  
  RESULTS
  Subjects with no previous PCV7 immunization history showed opsonic activity for serogroup 6 in 5-30% (according to serotype). In subjects vaccinated with a 3-dose primary series, 81% showed opsonic activity for serotypes 6B and 6D, and 29% showed opsonic activity for serotypes 6A and 6C. Among subjects vaccinated with a booster dose, all subjects had opsonic activity against serotype 6B. Subjects in the booster group with opsonic activity against serotypes 6A, 6C, and 6D were 100%, 78%, and 89%, respectively.
  
  
  CONCLUSIONS
  In subjects aged 12-23 months, an immune response is elicited after a primary series of immunizations with PCV7 for serotypes 6B and 6D, and a booster dose enhances a cross reactive immune response against serotypes 6A, 6C and 6D.
authors.affiliation: Department of Pediatrics, Ewha Womans University School of Medicine, Seoul, Korea. kaykim@ewha.ac.kr.
authors.forename: Hyunju
authors.initials: H
authors.lastname: Lee
authors.forename: Jung Hwa
authors.initials: JH
authors.lastname: Cha
authors.forename: Moon H
authors.initials: MH
authors.lastname: Nahm
authors.forename: Robert L
authors.initials: RL
authors.lastname: Burton
authors.forename: Kyung-Hyo
authors.initials: KH
authors.lastname: Kim
mesh_terms: D056738:Cross Protection; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D010587:Phagocytosis; D011008:Pneumococcal Infections / Q000276:immunology* / Q000382:microbiology*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage / Q000276:immunology*; D013296:Streptococcus pneumoniae / Q000145:classification / Q000235:genetics / Q000276:immunology*; D014611:Vaccination; D018074:Vaccines, Conjugate / Q000008:administration & dosage / Q000276:immunology
chemical_list: D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate